Note: Descriptions are shown in the official language in which they were submitted.
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BONDED COMPOSITE OPEN MESH STRUCTURAL TEXTILES
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to bonded composite open
mesh structural textiles primarily designed for use as structural
load bearing elements in earthwork construction applications such
as earth retention systems (in which the load bearing element is
used to internally reinforce steeply inclined earth or construction
fill materials to improve their structural stability), foundation
improvement systems (in which the load bearing element is used to
support and/or internally reinforce earth or foundation fill
materials to improve their load bearing capacity), pavement
improvement systems (in which the load bearing element is used to
internally reinforce flexible pavements or to support rigid modular
paving units to improve their structural performance and extend
their useful service lives) or erosion protection systems (in which
the load bearing element is used to confine or internally reinforce
earth or construction fill materials in structures which are
subject to erosion or which prevent erosion elsewhere by
dissipating wave energy in open water). While the materials of
this invention have many other diverse applications, they have been
primarily designed to embody unique characteristics which are
important in engineered earthwork construction and particular
emphasis is placed on such uses throughout this application.
2. Description of the Prior Art
Geogrids and geotextiles are polymeric materials used as
load bearing, separation or filtration elements in many earthwork
construction applications. There are four general types of
materials used in such applications: 1) integrally formed
'35 structural geogrids; 2) woven or cnitted textiles; 3) open mesh
woven or knitted textiles (which are generally configured to
resemble and compete with integrally formed structural geogrids);
and 4) non-woven textiles.
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Integrally formed structural geogrids are formed by
extruding a flat sheet of polymeric material, punching apertures in
the sheet in a generally square or rectangular pattern and then
uniaxially or biaxially stretching the .apertured sheet, or by
extruding an integrally formed mesh structure which constitutes a
sheet with apertures in a generally square or rectangular pattern,
and then uniaxially or biaxially stretching the apertured sheet.
Woven or knitted textiles are formed by mechanically interweaving
or interlinking polymeric fibers or fiber bundles with conventional
l0 textile weaving or knitting technologies. Open mesh woven textiles
are formed in this same manner and are normallv coated in a
subsequent process. Non-woven textiles are formed by various
techniques including overlaying and mechanically entangling
polymeric fibers, generally by needling, and in some processes the
entangled polymeric fibers are then re-oriented in a biaxial
stretching process, calendered and/or heat fused.
Integrally formed structural geogrids are well known in
the market and are an accepted embodiment in many earthwork
construction applications. Open mesh woven or knitted textiles,
generally characterized and marketed as textile geogrids, compete
directly with integrally formed structural geogrids in many
applications and have also established an accepted position in
earthwork construction markets. Competition between either of
these "geogrid" materials and conventional woven or knitted
textiles is less frequent. Woven or knitted textiles with low
basis ;weight tend to be used in separation and filtration
applications. Woven or knitted textiles with high basis weight
tend to be used in load bearing applications which are tolerant to
the load-elongation properties of such materials and which can
beneficially use the high ultimate tensile strength of such
materials. Non-woven textiles are generally subject to very high
elongation under load and are noz normally used in load bearing
earthwork construction applications. Competition between either of
the "geogrid" :materials and ron-woven textiles is negligible.
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The characteristics of _.integrally formed structural
geogrids and open mesh woven or knitted textiles are significantly
different in several respects. The integrally formed materials
exhibit high structural integrity with high initial modulus, high
junction strength and high flexural and torsional stiffness. Their
rigid structure and substantial cross sectional profile also
facilitate direct mechanical keying with construction fill
materials, with contiguous sections of themselves when overlapped
and embedded in construction fill materials and with rigid
mechanical connectors such as bodkins, pins or hooks. These
features of integrally formed structural geogrids provide excellent
resistance to movement of particulate construction fill materials
and the integrally formed load bearing elements relative to each
other, thereby preserving the structural integrity of foundation
fill materials or preventing pull out of the embedded load bearing
elements in earth retention applications.
Integrally formed structural geogrids interact with soil
or particulate construction fill materials by the process of the
soil or construction fill materials penetrating the apertures of
the rigid, integrally formed geogrid. The result is that the
geogrid and the soil or construction fill materials act together to
form a solid, continuously reinforced matrix. Both the
longitudinal load bearing members and the transverse load bearing
members and the continuity of strength between the longitudinal and
the transverse load bearing members of the geogrid are essential in
this continuous, matrix-like interlocking and reinforcing process.
If the junction between the longitudinal and the transverse load
bearing members fails, the geogrid ceases to function in this
manner and the confinement and reinforcement effects are greatly
reduced. Their rigid structure also facilitates their use over
very weak or wet subgrades where placement of such load bearing
materials arid subsecruent placement ~f construction fill materials
is difficult.
The open mesh woven or ::nitted materials exhibit higher
.~5 overall elongation under load. ~ower ;nitial modulus, softer hand
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and greater flexibility. With sufficient increase in the number of
fibers or fiber bundles comprising their structure they are capable
of achieving higher ultimate tensile strength than integrally
formed structural geogrids. However, they also exhibit low
junction strength which limits their effectiveness in direct
mechanical keying with construction fill materials, with contiguous
sections of themselves when embedded in construction fill materials
or with rigid mechanical connectors. As a result, such materials
are primarily used in applications which rely on a frictional
interface with construction fill materials to transfer structural
loads to the load bearing element and users of such materials also
avoid applications which involve load bearing connections with
rigid mechanical connectors. Also, their low flexural and
torsional stiffness limit their practical usefulness and
performance in certain earthwork applications such as construction
over very weak subgrades or construction fill reinforcement in
foundation improvement applications.
The attributes which are most pertinent to the use of
polymeric materials in structural load bearing earthwork
construction applications are:
(a) the load transfer mechanism by which structural forces
are transferred to the load bearing element,
(b) the load capacity of the load bearing element;
(c) the structural integrity of the load bearing element when
subjected to deforming forces in installation and use;
and
(d) the resistance of, the load bearing element to degradation
(i.e., loss of :~ey properties) when subject to
installation or long germ environmental stress.
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The limitations which open mesh woven or knitted textiles
exhibit with respect to the first three attributes listed above
primarily result from a lack of rigidity and tautness in the fibers
or fiber bundles in the junction zones of these materials in~which
many separate fibers or fiber bundles are interlinked, interwoven
or entangled in a manner which is characteristic of a woven or
a
knitted structure and which does not cause the load bearing fibers
or fiber bundles to be either taut or dimensionally stable relative
to each other. The limitations which such materials exhibit with
respect to the fourth attribute listed above primarily result from
degradation of their coating materials and separation of such
coating materials from the load bearing fibers.
Attempts have been made to dimensionally stabilize and
protect the fibers or fiber bundles in the junction zones of open
mesh woven or knitted textiles. For instance, such textiles are
normally coated with another material such as polyvinylchloride
after the principal textile structure is formed on a weaving or
knitting loom. This technique improves the dimensional stability
of the fibers or fiber bundles in the junction zone to some extent
and also provides some protection from abrasion to the fibers
throughout the textile. However, this technique has not delivered
sufficient junction strength or sufficient initial modulus to
enable such materials to be functionally comparable to integrally
formed structural geogrids or to be directly competitive with
integrally formed structural geogrids in certain demanding
earthwork construction applications which require or benefit from
load transfer by direct mechanical keying or high initial modulus
or high structural integrity or stiffness in the load bearing
element. The protective coatings also tend to degrade and separate
from the load bearing fibers, thereby reducing their effectiveness
in providing long term resistance to environmental degradation of
the load bearing fibers and also creating a potential shear failure
surface at ~he interface between ~ize Load bearing fibers and the
coating material.
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SUMMARY OF THE INVENTION
It is an object of the present invention to provide an
open mesh textile which has improved suitability for use as a
structural load bearing element in demanding earthwork construction
applications.
b
It is another object of the present invention to provide
an open mesh textile with improvements over the prior art in one or
more of the following attributes:
(a) its load transfer mechanism (specifically its suitability
for direct mechanical keying with construction fill
materials, with contiguous sections of itself when
overlapped and imbedded in construction fill materials
and with rigid mechanical connectors such as bodkins,
pins or hooks);
(b) its load capacity (specifically its initial modulus,
i.e., its resistance to elongation when initially subject
to load)
(c) its structural integrity (specifically its junction
strength and its flexural and torsional stiffness); and
(d) its durability (specifically its resistance to
degradation when subject to installation and long term
environmental stress).
These and other objects of the present invention will
become apparent with reference to the following specification and
claims.
Bonded composite open mesh structural textiles according
to the present invention are open mesh woven textiles formed from
at least two and preferably Three independent but complementary
polymeric components. The =first component, the load bearing
element, is a high tenacity, high initial modulus, low elongation
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monofilament or multifilament polymeric fiber or bundle of such
fibers with each fiber being of homogenous or bicomponent
structure. Where bicomponent fibers or fiber bundles are used to
form such load bearing elements it is possible to achieve improved
resistance to degradation (i.e., loss of key properties) when such
y materials are subject to installation and long term environmental
stress in use (i.e., by using a core material most suited to
achievement of desired mechanical properties and a different sheath
material most suited to achievement of desired durability
properties in a particular field of use). The second component, a
bonding element, is an independent polymeric material in
monofilament or multifilament form and of homogenous or bicomponent
structure which is used to encapsulate and bond the load bearing
fibers particularly in the junction zones of the open mesh textile
thereby strengthening the junction, stiffening the composite
material, increasing its resistance to elongation under load and
increasing its resistance to degradation when subject to
installation or long term environmental stress. The third
component, when used, is an effect or bulking fiber which increases
the cross section of the bonded composite open mesh structural
textile thereby further increasing its stiffness and increasing its
effectiveness in mechanically interlocking (keying) with
particulate construction fill materials.
In the bonded composite open mesh woven textile a
plurality of, warp fibers (commonly referred to as yarns) are
closely interwoven with a plurality of weft yarns. The weave
preferably includes a half cross or full cross leno weave. At
least a portion of the warp and weft yarns are first component load
bearing yarns. The second polymer component is used as required
for the bonding properties necessary for the finished product, and
especially to provide improved ;unction strength. The effect or
bulking yarns are used as warp and/cr weft yarns and/or leno yarns.
. The effect or bulking yarns Increase friction with adjacent yarns
to provide better stability and s~ructural integrity in the overall
material. Two or more effect or bulking yarns interlacing with one
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another provide the greatest stability and highest junction
strength. The effect or bulking yarns also provide the desired
bulk in the textile and relatively thick cross sectional profile
for the finished product to improve its stiffness and its
effectiveness in mechanically interlocking with particulate
construction fill materials.
The second component may be incorporated into the textile
in several ways. The second component may be provided by a fusible
bonding yarn, either monofilament or multifilament, which is
preferably a bicomponent yarn having a low melting temperature
sheath and a high melting temperature core. In the woven textile,
the fusible bonding yarns may be used as warp and/or weft yarns
and/or leno yarns to provide the improved junction strength.
Alternatively, the second component may be provided by a suitable
polymer applied and bonded to the textile by any of a number of
different processes after the textile leaves the loom. The second
component also may be provided by a combination of a fusible
bonding yarn and an additional polymeric material independently
applied and bonded to the textile.
In accordance with one embodiment of the invention where
a fusible bonding yarn is used, the woven textile is heated to melt
the fusible polymer component, i.e., to melt the monofilament
bonding fibers or the sheath of the bicomponent bonding fibers.
This causes the fusible polymer component to flow around and
encapsulate the other components of the textile and protects,
strengthens and stiffens the overall structure and particularly the
junctions. In accordance with another embodiment of the invention,
the woven textile is impregnated with a suitable polymer which
flows around and encapsulates the other components of the textile,
especially the junctions. The impregnated textile is then heated
to dry and/or cure the polymer to bond the yarns especially at the
junctions. In accordance with veL another embodiment of the
invention, a polymer sheet cr web is applied to the woven textile
and heated to melt the sheet or web causing the polymer to flow
around and encapsulate the other components of the textile.
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The materials produced according to the present invention
can also be modified for various applications by selection of the
type and number and location of the first component load bearing
yarns and the type and number and location of the second component
fusible bonding yarns and/or other independent polymeric bonding
materials, and the type and location of the optional third
component bulking yarns . Thus , the material can be custom tailored
for particular applications. Materials produced according to the
present invention can also easily be designed and manufactured to
achieve specific tensile properties in the longitudinal direction
or both the longitudinal and transverse directions. This
flexibility enables more efficient use of the instant invention in
demanding earthwork applications which often have widely varying
and site specific needs . The use of fusible yarns and/or other
polymeric bonding materials to strengthen the junctions and/or
increase overall material stiffness also permits increased
flexibility in the design and commercial use of such materials.
Inexpensive bulking yarns may also be used in a variety of
economical ways to provide bulk and increased cross sectional
profile without sacrificing strength or other desirable
characteristics. For example, some or all warp or weft yarn
bundles may be selected to provide a thick profile through the
addition of bulking yarns or additional strength yarns. The
resulting thick profile, either in all yarn bundles or in certain
selected yarn bundles, for example every sixth weft yarn bundle,
will provide improved resistance to pullout. The thick yarn bundle
profile in the bonded composite open mesh structural textile
functions in a manner similar to the vertical cross sectional faces
of an integrally formed structural geogrid. Finally, materials
produced according to the present invention can be manufactured
using conventional, inexpensive, :aidely available weaving equipment
which minimizes the cost of production of such materials.
Materials produced according to the present invention
have a number of advantages compared to conventional open mesh
'35 woven or knitted textiles, the collective effect of which is to
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render materials produced according to the present invention much
more suitable for use in demanding earthwork construction
applications. The primary benefits of the inventive concepts
embodied in materials produced according to the present invention
are described below:
Feature Benefit
1. Improved junction strength causes structural forces in
demanding earthwork
construction applications to be
transferred to the load bearing
elements of the instant
invention by means of positive
mechanical interlock with
construction fill materials as
well as by frictional interface
with such construction fill
materials; also enables use of
the instant invention in
applications requiring or
favoring use of rigid
mechanical connectors such as
bodkins, pins or hooks
2. Improved cross sectional causes load bearing elements
profile transversely oriented relative
to structural forces in
demanding earthwork
construction applications to
present an increased abutment
interface to particulate
construction fill materials,
thereby substantially -
increasing their resistance to
movement relative to such
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particulate construction fill
materials (commonly called pull
out resistance)
3. Improved initial modulus causes structural forces in
demanding earthwork
applications to be transferred
to the load bearing elements of
the instant invention at very
low strain levels, thereby
substantially reducing
deformation in the earthwork
structure and substantially
increasing the efficiency of
use of such load bearing
elements in demanding earthwork
construction applications
4. Improved flexural causes the matrix of
stiffness transversely oriented load
bearing elements in the instant
invention to resist in plane
deflection, thereby increasing
its ease of installation,
particularly over very weak or
wet subgrades and increasing
its capacity to support
construction fill materials
initially placed on top of such
~0 subgrades
5. improved torsional pauses the matrix of
stiffness Transversely oriented load
nearing elements in the instant
. 35 invention to resist in plane or
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rotational movement of
particulate construction fill
materials when subject to
dynamic loads such as a moving ,
vehicle causes in an aggregate
foundation for a roadway ,
thereby increasing the load
bearing capacity of the
particulate construction fill
materials and increasing the
efficiency of use of such load
bearing elements in such
demanding earthwork
construction applications
6. Improved resistance to causes the instant invention to
degradation have improved suitability for
use in earthwork construction
applications which involve
exposure to significant
mechanical stress in
installation or use and/or
involve exposure to significant
long term environmental (i.e.,
biological or chemical) stress
in use
7. Improved flexibility in enables widely disparate and
p r o d a c t d a s i g n a n d complementary properties to be
manufacture embodied in the instant
invention via the independent
polymeric materials chosen for
use in each of the three
components of the instant
~5 invention (the load bearing
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element, the bonding element
and the bulking element) or
chosen for use in the
independent polymeric materials
- comprising the core or sheath
components of any of these
three elements and also enables
the type and number and
location of all such components
of the instant invention to be
economically varied without
substantial modification of
manufacturing equipment
8. Improved efficiency in enables users of the instant
product use invention to exploit the
various product features and
the flexibility in choosing and
using variants of such features
all as described above to
achieve performance and
productivity gains in a wide
variety of earthwork
construction applications
9. Improved suitability for causes theinstant invention,
use in demanding earth-work by virtue of the collective
construction Features and benefits described
above, to have greater
0 opportunity for use in markets
involving demanding earthwork
construction applications than
zas heretofore been enjoyed by
oven mesh woven or knitted
5 Textiles
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BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a perspective view of a bonded composite open
mesh structural textile according to the present invention.
Fig. 2 is an exploded schematic plan view of a portion of
the bonded composite open mesh structural textile of Fig. 1.
Fig. 3 is an exploded schematic plan view of a portion of
a bonded composite open mesh structural textile construction
according to the present invention showing another weaving pattern.
Fig. 3 (A) is an exploded schematic plan view of a portion
of the bonded composite open mesh structural textile construction
of Fig. 3 showing a variation in the leno weave.
Fig. 3 (B) is an exploded schematic plan view of a portion
of the bonded composite open mesh structural textile construction
of Fig. 3 showing another variation in the leno weave.
Fig. 4 is an exploded schematic plan view of a portion of
a bonded composite open mesh structural textile construction
according to the present invention showing yet another weaving
pattern.
Fig. 5 is an exploded schematic plan view of a portion of
a bonded composite open mesh structural textile construction
according to the present invention showing a further weaving
pattern.
Fig. 6 is a schematic sectional view of a retaining wall
formed using bonded composite open mesh structural textiles
according to the present invention.
Fig. 7 is a schematic sectional view of a reinforced
embankment constructed over weak foundation soils using bonded
composite open mesh structural textiles according to the present
invention.
Fig. 8 is a schematic sectional view of a steepened
reinforced earth slope which increases the capacity of sludge
containment of a sludge containment pond using bonded composite
open mesh structural textiles according to the present invention.
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Fig. 9 is a schematic sectional view of a landfill liner
support system provided by a bonded composite open mesh structural
textile according to the present invention.
Fig. 10 is a schematic sectional view of a stabilized
soil veneer on a steeply inclined landfill liner provided by a
bonded composite open mesh structural textile according to the
present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to Figs. 1 and 2, the bidirectional woven
textile to is formed into the openwork apertured structure or open
mesh textile 12 of the present invention. Textile 10 is formed of
a plurality of spaced apart weft yarn bundles 14. Each weft yarn
bundle is formed of a plurality of weft, filling or pick yarns 16
( 16a-f ) . Each bundle 14 of weft yarns 16 includes edge weft or
pick yarns 16a and 16f. The weft yarn bundles 14 are woven
together with a plurality of spaced apart warp yarn bundles 18.
Each of the warp yarn bundles 18 is formed of a plurality of warp
yarns 20 (20a-h). Each bundle of warp yarns 18 includes edge warp
yarn pairs 20a-b and tog-h.
At the junctions or joints 22 of the open mesh textile
12, the weft yarns 16 are interlaced or interwoven with the warp
yarns 20. At least four weft yarns 16 are interlaced or interwoven
with at least four warp yarns 20 at the junctions or joints 22 of
the open mesh textile 12. As illustrated in Figs. 1 and 2, each
weft yarn 16 (e.g., 16d) is interlaced with the warp yarns 20
independently of adjacent weft yarns 16 (e.g., 16c and 16e), and
each warp yarn 20 (e.g., 20d) is interlaced with the weft yarns 16
independently of adjacent warp yarns 20 (e.g., 20c and 20e). The
weft yarns 16 and warp yarns 2 0 are interlaced in a plain weave
(1/1) as illustrated in Figs. 1 and 2. However, the weft yarns 16
and warp yarns 20 also could be interlaced in other relatively
highly interlaced weave patterns such as a twill weave (e. g., 1/2,
~35 2/1, 3/1, 1/3, 2/2, 3/3).
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As illustrated in Figs. 1 and 2, the warp ends of
adjacent warp yarn pairs 20a and 20b, 20c and 20d, 20e and 20f, and
20g and 20h, respectively, are alternately twisted in a right- and
left-hand direction crossing at 24 (180°) and 25 (180°) to
provide
a complete twist (360°) or full-cross leno weave between adjacent
weft yarn bundles 14. Alternatively, the warp ends of adjacent
warp yarns 20 are twisted in only one direction between adjacent
weft yarn bundles 14 to form a half twist (180°) or half-cross leno
weave (not shown) between adjacent weft yarn bundles 14.
The woven textile of the present invention may be formed
on any conventional loom such as a Rapier loom. As illustrated in
Figs. 1 and 2, each weft yarn bundle 14 has six weft yarns 16a-f
and each warp yarn bundle 18 has eight warp yarns 20a-h. The loom
will typically throw fourteen to twenty-four false picks for a
complete cycle of twenty to thirty picks. The maximum total picks
per inch will typically be about 20 to 36. The number of warp ends
per inch will typically be about 6 to 18.
The open mesh textile 12 has lateral or cross-machine
members 26 (weft yarn bundles 14) and longitudinal or machine
direction members 28 (warp yarn bundles 18) which interconnect at
the junctions 22 to define relatively large openings 30 through
which soil, water or other material may pass when the open mesh
textile 12 is placed in the earth. The openings 30 will typically
be about 3/4 to 1 inch. While openings 30 are illustrated as
square, the openings may be rectangular. If desired, the openings
may be up to 12 inches or more in the warp direction. There
could be as few as 6 to 10 weft yarns (in one cross member) per 12
inches of warp which would produce an unbalanced structure
analogous to a uniaxially oriented integrally formed structural
30 geogrid. The shape and size of the openings 30 will depend on the
performance requirements of the open mesh textiles: however, the
shape and size of the openings can be selected by adjusting the
relative positioning of the weft yarn bundles 14 and the warp yarn .
bundles 18. Open mesh textile 12 has a first side 32 and second
side 34.
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Figs. 3-5 show additional woven textile constructions
according to the present invention in which the same reference
numerals are used as in Fig. 1 for the same components or elements
except in the "loo", "200" and "300" series, respectively. More
specifically, Fig. 3 shows a woven textile construction 110 which
is similar to woven textile l0 of Fig. 1 except only the warp ends
1
of adjacent warp yarn pairs I20a and 120b, and 1208 and 120h,
respectively, encircle with a half twist at 124 (180°) and 125
(180°) to provide a complete twist (360°) or full-cross leno
weave
between adjacent weft yarn bundles 114. As with respect to Figs.
1 and 2, alternatively the warp ends of warp yarn pairs 120a and
l2ob, and l2og and l2oh, respectively, may encircle with only a
half twist (180°) between adjacent weft yarn bundles 114 to form a
half-cross leno weave 136 between adjacent weft yarn bundles 114 as
shown in Fig. 3 (A) . As a further alternative, the warp ends of
adjacent warp yarn pairs 120a and 120b, and 120g and 120h,
respectively, may form a half-cross leno weave 138 between adjacent
weft yarns 116a-f as shown in Fig. 3(B), i.e., the warp ends may
encircle with a half twist (180°) between adjacent weft yarns 116a
f.
Fig. 4 shows another woven textile construction 200. In
this construction; a leno yarn 236 is woven in yet another form of
half-cross leno weave into textile construction 210. Leno yarn 236
is woven at section 236a diagonally to warp yarn bundle 218 along
second side 234 of textile 212, at section 236b parallel to warp
yarn bundle 218 along first side 232 of textile 212, and at section
236c diagonally to warp yarn bundle 218 along second side 234 of
textile 212. Alternatively, section 236b of leno yarn 236 may be
interlaced or interwoven with weft yarns 216 of weft yarn bundle
214. Leno yarn 236 is woven under tension and gives firmness and
compactness to weft and warp yarn bundles 214 and 218, preventing
slipping and displacements of weft yarns 216 and warp yarns 220.
Leno yarn 236 also increases the strength of junction 222.
Fig. 5 shows a woven textile construction 310 which is
~35 similar to woven textile construction 110 of Fig. 3 except two leno
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yarns 336 and 338 are woven in still another half-cross leno weave
into woven textile construction 310 and both sections 336b and 338b
of leno yarns 236 and 238, respectively, are interlaced or
interwoven with weft yarns 316 of weft yarn bundle 314. Also, leno
yarn 338 is woven at section 338a diagonally to warp yarn bundle
318 along first side 332 of textile 312 and at section 338c
diagonally to warp yarn bundle 318 along first side 332 of textile
312. Both leno yarns 336 and 338 are woven under tension to
prevent slipping and displacements of weft yarns 316 and warp yarns
320 and to increase the strength of junction 322.
Figs. 3-5 are exploded schematic plan views like Fig. 2.
However, it should be understood that the junctions 122, 222 and
322 in Figs. 3-5, respectively, are tightly interlaced or
interwoven in similar manner to the junction 22 illustrated in Fig.
1.
'A majority of the weft and warp yarns are preferably the
load bearing member, namely, the high tenacity, low modulus, low
elongation mono- or multifilament yarns. Suitable mono- or
multifilament yarns are formed from polyester, polyvinylalcohol,
nylon, aramid, fiberglass, and polyethylene naphthalate.
The load bearing member should have a strength of at
least about 5 grams per denier, and preferably at least about 9 to
10 grams per denier. The initial Young's modulus of the load
bearing member should be about 100 grams/denier, preferably about
150 to 400 grams/denier. The elongation of the load bearing member
should be less than about 180, preferably less than about 100. The
load bearing member will typically have a denier of about 1,000 to
2,000, preferably about 2,000 to 8,000.
The textiles can be produced with approximately equal
strength in the longitudinal or machine direction and in the
lateral or cross-machine direction. Alternatively, the textiles
can be produced with greater strength in either the longitudinal
direction or the lateral direction. The selection of the strength .
characteristics of the textiles will be determined based on the
~5 requirements of the application design. .
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The fusible bonding yarns, if incorporated into the
weave, are used as warp and/or weft yarns and/or ~leno yarns as
required for the desired bonding properties, and especially the
bonding properties needed to form the necessary strength of the
5' junctions. When the textile is heated to melt the fusible polymer
component, the fusible polymer component flows around and
encapsulates other components of the textile bonding and
stabilizing the textile structure and protecting the load bearing
yarns from abrasion and chemical attack. The fusible yarn may be
a monofilament or multifilament form of yarn and of homogeneous or
bicomponent composition.
The preferred fusible yarn is a bicomponent yarn such as
one having a low melting sheath of polyethylene, polyisophthalic
acid or the like, and a high melting core of polyester or the like.
The bicomponent yarn also may be a side-by-side yarn in which two
different components (one with low melting temperature and one with
high melting temperature) are fused along the axis and having an
asymmetrical cross-section, or a biconstituent yarn having one
component dispersed in a matrix of the other component, the two
components having different melting points. The low and high
melting components also may be polyethylene and polypropylene,
respectively, different melting point polyesters, or polyamide and
polyester, respectively. The bicomponent yarn will typically be
composed of 30 to 70% by weight of the low melting temperature
component, and 70 to 30% by weight of the high melting temperature
component. The fusible yarn also may be an extrusion coated yarn
having a low melting point coating or a low melting point yarn
(e. g., polyethylene) employed in the textile structure side-by-side
with other yarns.
As an alternative to using fusible bonding yarns, or in
addition to using fusible bonding yarns, the textile is impregnated
with a suitable polymer after it leaves the loom. The textile may
be passed through a polymer bath or sprayed with a polymer. The
impregnating material typically comprises an aqueous dispersion of
~35 the polymer. In the impregnation process, the polymer flows around
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WO 96/35833 PCT/US96/06762
and encapsulates the other components of the textile, especially
the junctions of the textile. The impregnated textile is then
heated to dry and/or cure the polymer to bond the yarns especially
at the junctions.
The polymer may be a urethane, acrylic, vinyl, rubber or
other suitable polymer which will form a bond with the yarns used
in the textile. The urethane polymer may be, for example, an
aqueous dispersible aliphatic polyurethane, such as a polycarbonate
polyurethane, which may be crosslinked to optimize its film
properties, such as with an aziridine crosslinker. Suitable
urethane polymers and crosslinkers are available commercially from
Stahl USA, Peabody, Massachusetts (e. g., UE-41-503 aqueous
polyurethane and KM-10-1703 aziridine crosslinker) and Sanncorre
Industries, Inc., Loeminister, Mass. (e. g., SANCURE~ 815 and 2720
polyurethane dispersions). The acrylic polymer may be, for
example, a heat reactive acrylic copolymer latex, such as a heat
reactive, carboxylated acrylic copolymer latex. Suitable acrylic
latexes are available from BF Goodrich, Cleveland, Ohio (e. g.,
HYCAR~ 26138 latex, HYCAR~26091 latex and HYCAR~ 26171 latex). The
vinyl polymer may be a polyvinylchloride polymer. The rubber
polymer may be neoprene, butyl or styrene-butadiene polymer.
As another alternative to using fusible bonding yarns, or
in addition to using fusible bonding yarns, a polymer sheet or web
is applied to the textile after it leaves the loom and the
textile/polymer sheet or web is heated to melt the polymer sheet or
web causing the polymer to flow around and encapsulate the other
components of the textile. The polymer sheet or web is typically
in nonwoven form. The polymer sheet or web may be a polyester,
polyamide, polyolefin or polyurethane sheet or web. Suitable
polymer sheets are available commercially from Bemis Associates
Inc., Shirley, Massachusetts, as heat seal adhesive films.
Suitable polymer webs are available commercially from Bostik Inc.,
Middleton, Massachusetts fe.g., Series PE 65 web adhesive). .
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WO 96/35833 PCT/US96/06762
The bonding process results in chemical and/or mechanical
bonds throughout the structure of the textile, and particularly the
junctions.
The effect or bulking yarns are used as warp and/or weft
yarns- and/or leno yarns. The effect or bulking yarns increase
friction with adjacent yarns to provide better stability (fiber to
fiber cohesion). Two or more effect or bulking yarns interlacing
with one another provide the greatest stability and highest joint
strength. The effect or bulking yarns also provide the desired
bulk in the textile and relatively thick profile of the finished
product. The bulking yarns are generally made from low cost,
partially oriented, polyester, polyethylene or polypropylene yarns
or the like. The individual bulking yarn components will typically
have a denier of about 150 to 300, preferably about 300 to about
1,000.
The bulking yarns may be friction spun or textured yarns.
Textured yarns are produced from conventional yarns by a known air
texturing process. The air texturing process uses compressed air
to change the texture of a yarn by disarranging and looping the
filaments or fibers that make up the yarn bundle. The texturing
process merely rearranges the structure of the yarn bundle with
little changes in the basic properties of the individual filaments
or fibers occurring. However, the higher the bulk, the higher the
loss in strength and elongation. Friction spun yarns are produced
by the DREF2 process from Fehere AG in Linz, Austria.
In addition to using individual load bearing yarns, the
present invention also contemplates forming composite yarns prior
to textile formation in which the load bearing yarn is combined
with a fusible bonding yarn or a bulking yarn. The composite may
be formed using air jet texturing in which the load bearing yarn
comprises the core and the fusible bonding yarn or bulking yarn is
textured. The core is fed with minimal overfeed and with an excess
quantity of fusible or bulking yarn with substantially higher
overfeed. The compressed air rearranges and loops the filaments or
~35 fibers of the fusible yarn or bulking yarn to increase the bulk of
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WO 96/35833 PCT/US96/06762
the composite yarn. Composite yarns incorporating the load bearing
yarn may also be made by known techniques such- as twisting or
cabling. The fusible yarn, especially of the monofilament type,
also may be combined with the bulking yarn prior to textile
formation such as by parallel end weaving, or by twisting, cabling
or covering (single or double helix cover).
Referring to Figs. 1-5 again, the fusible bonding yarn or
bulking yarn would typically be used as warp yarns 20a and 20h, or
warp yarn pairs 20a-b and 20g-h, in Figs. 1-2. In Fig. 3, warp
yarns 120a and 120h, or warp yarn pairs 120a-b and 120g-h, would
typically be fusible yarns or bulking yarns . In Figs . 4 and 5, the
fusible yarn or bulking yarn could be the leno yarn 236, and leno
yarns 336 and 338, respectively. However, the fusible yarn or
bulking yarn could be incorporated into the woven textiles
illustrated in Figs. 1-5 in many other ways.
A preferred construction of the present invention is
illustrated in Fig. 3(B) in which the warp yarns 120c-f are high
tenacity, high modulus, low elongation yarns (e. g.,
polyvinyl alcohol) , the warp yarns 120a and 120b, and 120g and 120h,
are fusible bonding yarns (e.g., a bicomponent yarn having a low
melting point polyisophthalic acid sheath and a high melting point
polyester core) or bulking yarns (e. g., air jet textured
polyester), and the weft yarns 116x-f are composite yarns having a
load bearing yarn core and bulking yarn (e. g., an air jet textured
?5 yarn having a polyvinylalcohol core and a polyester bulking). The
textile preferably includes a polymer impregnation formed by
dipping the textile in a polymer bath (e. g., urethane or acrylic).
The woven textile of the present invention also may
include electrically conductive components as warp and/or weft
yarns. The electrically conductive components may be metal yarns
or strips (e.g., copper), polymeric yarns, either monofilament or
multifilament, rendered electrically conductive by adding fillers
(e.g., carbon black, copper, aluminum) in the polymer during
extrusion, an electrically conductive filament of a multifilament
35 yarn, or a polymeric yarn having an electrically -conductive
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WO 96!35833 PCTIiTS96/06762
coating. The electrically conductive components permit breaks to
be detected in the woven textile in a known manner. The
electrically conductive components also permit failures in other
components of a composite civil engineering structure to be
detected. The electrically conductive components also permit the
woven textile to be used in electrokinetic and related
applications.
The woven textile of the present invention can be
finished by applying heat energy (e. g., calendaring, radio
frequency energy, microwave energy, infra-red energy and tentering)
to the material to soften the fusible yarn (e.g., the sheath of a
bicomponent yarn), dry and/or cure the polymer impregnating the
textile or melt the polymer sheet or web to lock the yarns and
textile material in place.
The results of the heating or finishing process are:
(a) the yarn bundles are protected against impact and
abrasion;
(b) the textile is protected against impact and abrasion;
(c) the yarn bundles are stiffened with better resistance
to elongation and with lower ultimate elongation;
(d) the textile is stiffened with better resistance to
elongation and with lower ultimate elongation;
(e) the yarn bundles are frozen in a fixed bulk for
better soil textile interaction;
( f ) the textile is frozen in a fixed bulk for better soil
textile interaction; and
(g) the junctions are protected, strengthened and
stiffened.
Fig. 6 shows a retaining wall 400 formed using the bonded
composite open mesh textile 402 le.g., textile 12 of Figs. 1 and 2,
textile 112 of Fig. 3 , textile 212 of Fig. 4 , or textile 312 of
Fig. 5) of the present invention. ~oundation or substrate 404 is
graded to a desired height and slope. detaining wall 406 is formed
from a plurality of retaining wall elements 406a. A plurality of
'5 bonded composite open mesh structural textiles 402 are attached to
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WO 96/35833 PCT/US96/06762
the retaining wall 406 at 408. The open mesh structural textiles
402 are separated by a plurality of fill layers 410. Using this
construction, random fill 412 is retained and held in place.
The retaining wall 406 is illustrated generically as ,
comprising a plurality of courses of modular wall elements 406a
such as conventional cementitious modular wall blocks. It is to be
understood, however, that similar wall structures can be formed
using modular wall blocks formed of other materials, including
plastic. Likewise, retaining walls incorporating the bonded
composite open mesh structural textiles of this invention can be
constructed with cast wall panels or other conventional facing
materials.
While no detail is shown for connection of the bonded
composite open mesh structural textiles to the retaining wall
elements, various techniques are conventionally used, including
bodkin connections, pins, staples, hooks or the like, all of which
may be readily adapted by those of ordinary skill in the art for
use with the bonded composite open mesh structural textiles of this
invention.
When embankments are constructed over weak foundation
soils the pressure created by the embani~nent can cause the soft
soil to shear and move in a lateral direction. This movement and
loss of support will cause the embankment fill material to shear
which results in a failure of the embankment. This type of failure
can be prevented by the inclusion oz bonded composite open mesh
structural textiles 420 (e.g. , textile 12 of Figs. 1 and 2, textile
112 of Fig. 3, textile 212 of Fig. 4, or textile 312 of Fig. 5) of
the present invention in the lower portions of the embankment 422
as shown in Fig. 7. The bonded composite open mesh structural
textiles 420 provide tensile strength that prevents the embankment
from failing.
Reinforced earth structures may be built to steep slope
angles which are greater Khan zhe natural angle of repose of the
fill material by the inclusion of bonded composite open mesh
:;5 structural textiles. Steep slopes can be used in many applications
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W O 96135833 PCT/US96/06762
to decrease the amount of fill required for a given earth
structure, increase the amount of usable space at the top of the
slope, decrease the intrusion of the toe of the slope into
. wetlands, etc. In Fig. 8; a steep slope dike addition is shown.
By using steep slopes 430, the amount of fill required to raise the
dike elevation is reduced and the load that is placed on both the
existing containment dike 432 and on the soft sludge 434 is also
reduced. A dramatic increase in containment capacity is achieved
through the use of steep slopes 430 reinforced with open mesh
structural textiles 436 (e. g., textile 12 of Figs. 1 and 2, textile
112 of Fig. 3, textile 212 of Fig. 4, or textile 312 of Fig. 5) of
the~present invention.
When embedding the bonded composite open mesh structural
textiles of this invention in a particulate material such as soil
or the like, the particles of aggregate engage the upper and lower
surfaces of the textile and,"strike through" the openings thereby
forming a reinforcing and stabilizing function.
In addition to their earth reinforcement applications,
the bonded composite open mesh structural textiles of this
invention are especially useful in landfill and industrial waste
containment constructions. Regulations require that the base and
side slopes of landfills be lined with an impermeable layer to
prevent the leachate from seeping into natural ground water below
the landfill. When landfills are located over terrain which is
compressible or collapsible, as in the case of Karst terrain, the
synthetic liner will deflect into the depression. This deflection
results in additional strains being induced into the liner which
can cause failure of the liner and seepage of the leachate into the
underlying ground water thus causing contamination. Through the
use of the high tensile strength of textile 440 (e.g., textile 12
of Figs. 1 and 2, textile 112 of Fig. 3, textile 212 of Fig. 4, or
textile 312 of Fig. 5) of the present invention as shown in Fig. 9
liner 442 support can be provided by positioning the textile 440
immediately below the liner 442. Should any depression 444 occur,
the high tensile capacity of the bonded composite open mesh
CA 02217536 1997-10-06
WO 96/35833 PCT/L1S96/06762
structural textile 440 provides a "bridging" affect to span the
depression and to minimize the strain induced into the liner 442
thereby helping to protect the landfill system from failure.
Construction of landfills requires that the geomembrane ,
liners be placed across the bottom of the landfill and up the side
slopes of the landfill as well. In order to protect this liner, a
layer of cover soil, known as a veneer, which has a dual purpose of
liner protection against punctures from waste material placement
and leachate collection if the cover soil has defined permeability
is normally placed on top of the liner. Since the surface of the
liner is smooth, the cover soil can fail by simply sliding down the
slope since the friction between the soil and the liner is too
small to support the weight of the soil layer. This type of
failure can be prevented by the placement of a textile 450 (e. g.,
textile 12 of Figs. 1 and 2, textile 112 of Fig. 3, textile 212 of
Fig. 4, or textile 312 of Fig. 5) of the present invention as showr_
in Fig. 10 anchored at the top and extending down to the toe of the
slope 452. The apertures (e. g., 30 in Figs. 1 and 2, 130 in Fig.
3, 230 in Fig. 4 and 330 in Fig. 5) of the textile 450 allow the
cover soil 454 to interlock with the textile 450 and the textile
450 in turn provides the tensile force required to hold this block
of soil in place, thus eliminating the sliding on the liner 456.
Bonded composite open mesh structural textiles of the
present invention also may be used in other earthwork construction
applications to reinforce soil or earth structures such as
foundation and pavement improvement systems and erosion protection
systems. Additionally, these textiles may be used in the
construction of geocells or retaining walls for marine use to
control land erosion adjacent to waterways such as rivers, streams,
lakes and oceans.
As indicated, while the textile materials of this
invention have particular utility in earthwork construction
applications, they are also adapted for any application where grid
or net products have been used heretofore. For example, the novel
~5 textiles described herein have excellent strength and related
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WO 96/35833 PCTlL1S96/06762
characteristics for use in the formulation of gabions as well as in
fencing applications or safety barriers. Additionally, they may be
readily adapted for use in seat cushions, as mattress insulators
and in diverse packaging applications, including pallet wraps and
the like, and in various original equipment manufacturing
applications.
Having described the invention, many modifications
thereto will become apparent to those skilled in the art to which
it pertains without deviation from the spirit of the invention as
l0 defined by the scope of the appended claims.
27
